Vehicle assembly lines typically include robotic welders for welding parts of vehicles together to effect assembly. Ordinarily, the parts to be welded are first loaded into a frame, referred to as a "tool", the position of which is translationally fixed. During loading, the parts are positioned and clamped in a predetermined orientation relative to each other. The parts are then spot welded together by the robotic welders. After spot welding, the clamps open, and the parts are extracted from the tool and moved to another location for finished welding.
To enable the robotic welders to weld parts together, end effectors having six degrees of freedom are associated with the welders. Consequently, the end effectors of the welders can move in accordance with a computer-controller program in six degrees of freedom, as required to undertake vehicle assembly.
While effective, such systems require several assembly lines, and the assembly lines generally require significant modifications and extended time during which production is halted to change the model of vehicle being assembled. The present invention recognizes, however, that the time and effort to undertake such so-called model change over can be reduced.
Moreover, assembly line workers are required to load the parts to be assembled into their respective frames, prior to processing by the robotic welders. It will be appreciated that a frame which can be conveniently and ergonomically loaded by one person, however, may not facilitate easy and ergonomic loading by another person. Unfortunately, existing fixed assembly frames do not provide for selectively establishing a load orientation that can be tailored to more than one person.
Accordingly, it is an object of the present invention to provide a vehicle assembly system which is adaptable to more than one model and versatile. Another object of the present invention is to provide a vehicle assembly system which can be used in conjunction with robotic welders having six degrees of freedom, to essentially establish a seventh degree of freedom. Still another object of the present invention is to provide a vehicle assembly system in which a plurality of user-selectable vehicle part loading positions can be established. Yet another object of the present invention is to provide a vehicle assembly system which is easy to use and cost-effective.